Control of monodisperse particle size of styrenic–acrylate copolymers in dispersion copolymerization

Syntheses of monodisperse poly[(styrene)‐co‐(n‐butyl acrylate)] and poly[(styrene)‐co‐(2‐ethylhexyl acrylate)] were carried out by dispersion polymerization. The reactions were performed in the mixed solvent of ethanol–water in the presence of azo‐bisisobutyronitrile and poly(N‐vinylpyrrolidone) as the initiator and dispersant, respectively. The effects of reaction parameters, that is the type and concentration of dispersant, ratio of the mixed solvent, reaction temperature, agitation rate, monomer composition between styrene and n‐butyl acrylate or 2‐ethylhexyl acrylate, crosslinking agent and reaction time on the particle size, size distribution and average molecular weights of the resulting copolymer were thoroughly investigated. The resulting copolymer particles were smooth on their spherical surface and the sizes were in the range 0.6–1.8 µm with a narrow size distribution. In most cases, a correlation between small particle sizes with high average molecular weights was observed. The average particle size generally increased with increasing reaction temperature, time and acrylate monomer content. In contrast, the particle size decreased as the molecular weight, concentration of dispersant, polarity of the medium or agitation rate was increased. The glass transition temperature (T_g) of the copolymers can be controlled by the mole ratio of the comonomer. The T_g values decreased when the content of acrylate monomers in the copolymer increased, and T_g values of the synthesized copolymer were in the range 66–102 °C. Instead of using n‐butyl acrylate monomer in the copolymerization, 2‐ethylhexyl acrylate copolymerization with styrene resulted in insignificant changes in the particle sizes but there were significant decreases in T_g values. In this study, the monodisperse particles can be obtained by monitoring the appropriate conditions regarding PVP K‐30 (2–8 wt%), ethanol/water (90/10 wt%), the reaction temperature (70 °C) and the agitation rate (100 rpm). © 2000 Society of Chemical Industry     

Synthesis and characterization of cassava starch graft poly(acrylic acid) and poly[(acrylic acid)‐co‐acrylamide] and polymer flocculants for wastewater treatment

Starch‐g‐poly(acrylic acid) and poly[(acrylic acid)‐co‐acrylamide] synthesized via chemically crosslinking polymerization were then each mixed with inorganic coagulants of aluminum sulfate hydrate [Al₂(SO₄)₃·18H₂O], calcium hydroxide [Ca(OH)₂], and ferric sulfate [Fe₂(SO₄)₃] in a proper ratio to form complex polymeric flocculants (CPFs). All CPFs exhibited low water absorbency than those of the uncomplexed superabsorbent copolymers. The color reduction by the CPFs was tested with both synthetic wastewater and selected wastewater samples from textile industries. The synthetic wastewater was prepared from a direct dye in a concentration of 50 mg dm^?3 at pH 7. The CPFs of poly[(acrylic acid)‐co‐acrylamide] with calcium hydroxide at a ratio of 1:2 is the most effective CPF for the wastewater color reduction. The CPF concentration of 500 mg dm^?3 could reduce the color of the synthetic wastewater containing the direct dye solution by 95.4% and that of the industrial wastewater by 76%. Starch‐g‐poly(acrylic acid)/Ca(OH)₂ CPF can reduce the synthetic direct dye and the industrial wastewater by 74% and 18%, respectively. Chemical oxygen demand, residual metal ion concentrations, pHs, turbidity of the wastewater were also investigated and the potential use of the complex polymer flocculants for textile wastewater treatment was indicated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2915–2928, 2006     

Determination of monomer reactivity ratios using in situ FTIR spectroscopy for maleic anhydride/norbornene‐free‐radical copolymerization

Monomer reactivity ratios for maleic anhydride (MAH) and norbornene (Nb) free‐radical copolymerizations were estimated by using a linear graphical method, which is based upon the terminal model developed by Mayo and Lewis. Reactions were performed by using optimized reaction conditions that were previously determined. MAH/Nb copolymerizations (3 mol % AIBN initiator, 60% solids in THF, 65°C, 24 h). Copolymerization data were collected via in situ FTIR to low degrees of conversion (～ 10%) for copolymerizations of MAH and Nb. The following five different MAH/Nb comonomer feed molar ratios were analyzed: 40/60, 45/55, 50/50, 55/45, and 60/40. Conversion data that were measured with in situ FTIR were employed in the rearranged copolymer composition equation to estimate MAH and Nb reactivity ratios. Both of the reactivity ratios were determined to be near 0 (r_MAH = 0.02, r_Nb = 0.01), which was indicative of an alternating copolymerization mechanism. The highest observed rate constant for copolymerization was obtained at an equal molar concentration of monomers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3240–3246, 2004     

Preparation and characterization of polystyrene/titanium dioxide composite particles containing organic ultraviolet‐stabilizer groups

Polystyrene/titanium dioxide (TiO₂) composite particles containing organic ultraviolet (UV)‐stabilizer groups were prepared by the emulsion copolymerization of styrene and 2‐hydroxy‐4‐(3‐methacryloxy‐2‐hydroxylpropoxy)benzophenone with sodium sulfopropyl lauryl maleate as a surfactant in the presence of rutile TiO₂ modified with 3‐(trimethoxysilyl) propyl methacrylate, and the product was poly[styrene‐co‐sodium sulfopropyl lauryl maleate‐co‐2‐hydroxy‐4‐(3‐methacryloxy‐2‐hydroxylpropoxy) benzophenone] [poly(St‐co‐M12‐co‐BPMA)]/TiO₂ composite particles. The structures of the composite particles were characterized with Fourier transform infrared spectroscopy, ultraviolet–visible (UV–vis) absorption spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The Fourier transform infrared and UV–vis measurements showed that poly(St‐co‐M12‐co‐BPMA) was grafted from the surface of TiO₂, and this copolymer possessed a high absorbance capacity for UV light, which is very important for improving the UV resistance of polystyrene. The thermogravimetric analysis measurements indicated that the percentage of grafting and the grafting efficiency could reach 513.9 and 59.9%, respectively. The differential scanning calorimetry measurement indicated that the glass‐transition temperature of the poly(St‐co‐M12‐co‐BPMA)/TiO₂ composite particles was higher than that of poly (St‐co‐M12‐co‐BPMA).These research results are very important for preparing polystyrene with high UV resistance. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

The synthesis of PHA‐g‐(PTHF‐b‐PMMA) multiblock/graft copolymers by combination of cationic and radical polymerization

A new and promising method for the diversification of microbial polyesters based on chemical modifications is introduced. Poly(3‐hydroxy alkanoate)‐g‐(poly(tetrahydrofuran)‐b‐poly(methyl methacrylate)) (PHA‐g‐(PTHF‐b‐PMMA)) multigraft copolymers were synthesized by the combination of cationic and free radical polymerization. PHA‐g‐PTHF graft copolymer was obtained by the cationic polymerization of THF initiated by the carbonium cations generated from the chlorinated PHAs, poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV), and poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHx) in the presence of AgSbF₆. Therefore, PHA‐g‐PTHF graft copolymers with hydroxyl ends were produced. In the presence of Ce⁺⁴ salt, these hydroxyl ends of the graft copolymer can initiate the redox polymerization of MMA to obtain PHA‐g‐(PTHF‐b‐PMMA) multigraft copolymer. Polymers obtained were purified by fractional precipitation. In this manner, their γ‐values (volume ratio of nonsolvent to the solvent) were also determined. Their molecular weights were determined by GPC technique. The structures were elucidated using ¹H‐NMR and FTIR spectroscopy. Thermal analyses of the products were carried out using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Stabilized electrospinning of heat stimuli/in situ crosslinkable nanofibers and their self‐same nanocomposites

We present a strategy for stabilizing the morphological integrity of electrospun polymeric nanofibers by heat stimuli in situ crosslinking. Amorphous polymer nanofibers, such as polystyrene (PS) and its co‐polymers tend to lose their fiber morphology during processing at temperatures above their glass transition temperature (T_g) typically bound to happen in nanocomposite/structural composite applications. As an answer to this problem, incorporation of the crosslinking agents, phthalic anhydride (PA) and tributylamine (TBA), into the electrospinning polymer solution functionalized by glycidylmethacrylate (GMA) copolymerization, namely P(St‐co‐GMA), is demonstrated. Despite the presence of the crosslinker molecules, the electrospinning polymer solution is stable and its viscosity remains unaffected below 60 °C. Crosslinking reaction stands‐by and can be thermally stimulated during post‐processing of the electrospun P(St‐co‐GMA)/PA‐TBA fiber mat at intermediate temperatures (below the T_g). This strategy enables the preservation of the nanofiber morphology during subsequent high temperature processing. The crosslinking event leads to an increase in T_g of the base polymer by 30 °C depending on degree of crosslinking. Crosslinked nanofibers are able to maintain their nanofibrous morphology above the T_g and upon exposure to organic solvents. In situ crosslinking in epoxy matrix is also reported as an example of high temperature demanding application/processing. Finally, a self‐same fibrous nanocomposite is demonstrated by dual electrospinning of P(St‐co‐GMA) and stabilized P(St‐co‐GMA)/PA‐TBA, forming an intermingled nanofibrous mat, followed by a heating cycle. The product is a composite of crosslinked P(St‐co‐GMA)/PA‐TBA fibers fused by P(St‐co‐GMA) matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44090.     

Graft copolymerization of thiophene onto polystyrene synthesized via nitroxide‐mediated polymerization and its polymer − clay nanocomposite

A new strategy for graft copolymerization of thiophene onto a polystyrene (PSt) backbone by a multi‐step process is suggested and the effects of an organoclay on the final properties of the graft copolymer sample are described. For this purpose, first poly(styrene‐co‐4‐chloromethyl styrene) [P(St‐co‐CMSt)] was synthesized via nitroxide‐mediated polymerization. Afterwards, the chlorine groups of P(St‐co‐CMSt) were converted to thiophene groups using the Kumada cross‐coupling reaction and thiophene‐functionalized PSt multicenter macromonomer (ThPStM) was synthesized. The graft copolymerization of thiophene monomers onto PSt was initiated by oxidized thiophene groups in the PSt chains after addition of ferric chloride (FeCl₃), an oxidative catalyst for polythiophene synthesis, and FeCl₃‐doped polythiophene was chemically grafted onto PSt chains via oxidation polymerization. The graft copolymer obtained was characterized by ¹H NMR and Fourier transform infrared spectroscopy, and its electroactivity behavior was verified under cyclic voltammetric conditions. Finally, PSt‐g‐PTh/montmorillonite nanocomposite was prepared by a solution intercalation method. The level of dispersion of organoclay and the microstructure of the resulting nanocomposite were probed by means of XRD and transmission electron microscopy. It was found that the addition of only a small amount of organoclay (5 wt%) was enough to improve the thermal stabilities of the nanocomposite.© 2013 Society of Chemical Industry     

Effect of in situ polymerization conditions of methyl methacrylate on the structural and morphological properties of poly(methyl methacrylate)/poly(acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene)‐g‐styrene) PMMA/AES Blends

In this study, the structural and morphological properties of poly(methyl methacrylate)/poly(acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene‐g‐styrene) (PMMA‐AES) blends were investigated with emphasis on the influence of the in situ polymerization conditions of methyl methacrylate. PMMA‐AES blends were obtained by in situ polymerization, varying the solvent (chloroform or toluene) and polymerization conditions: method A—no stirring and air atmosphere; method B—stirring and N₂ atmosphere. The blends were characterized by infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and dynamic mechanical analysis (DMA). The results showed that the PMMA‐AES blends are immiscible and present complex morphologies. This morphology shows an elastomeric dispersed phase in a glassy matrix, with inclusion of the matrix in the elastomer domains, suggesting core shell or salami morphology. The occlusion of the glassy phase within the elastomeric domains can be due to the formation of graft copolymer and/or phase inversion during polymerization. However, this morphology is affected by the polymerization conditions (stirring and air or N₂ atmosphere) and by the solvent used. The selective extraction of the blends' components and infrared spectroscopy showed that crosslinked and/or grafting reactions occur on the elastomer chains during MMA polymerization. The glass transition of the elastomer phase is influenced by morphology, crosslinking, and grafting degree and, therefore, T_g depends on the polymerization conditions. On the other hand, the behavior of T_g of the glassy phase with blend composition suggests miscibility or partial miscibility for the SAN phase of AES and PMMA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of cross‐linkable poly(phthalazinone ether ketone)s

A novel class of crosslinkable poly(phthalazinone ether ketone)s with relative high molecular‐weight and good solubility were successfully synthesized by the copolymerization of bisphthalazinone containing monomer, 3,3′‐diallyl‐4,4′‐dihydroxybiphenyl and 4,4′‐di‐ fluorobenzophenone. The synthesized polymers with inherent viscosities in the range of 0.42 to 0.75 dL/g can form flexible and transparent membranes by casting from their solution. The crosslinking reaction of these polymers can be carried out by thermally curing of the virgin polymers in or without the presence of crosslinking agent. The experimental results demonstrated that the crosslinking reaction also occurred to some extent during the polymerization. The crosslinked polymers exhibited equivalent glass transition temperature (T_g) at lower crosslinking density, and showed higher T_g than virgin polymers at higher crosslinking density. The crosslinked high‐temperature polymer can be used as the base material for high temperature adhesive, coating, enamel material, and composite matrices. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Competitive hydrogen bonding mechanisms underlying phase behavior of triple poly(N‐vinyl pyrrolidone)–poly(ethylene glycol)–poly(methacrylic acid‐co‐ethylacrylate) blends

Differential scanning calorimetry (DSC) of triple blends of high molecular weight poly(N‐vinyl pyrrolidone) (PVP) with oligomeric poly(ethylene glycol) (PEG) of molecular weight 400 g/mol and copolymer of methacrylic acid with ethylacrylate (PMAA‐co‐EA) demonstrates partial miscibility of polymer components, which is due to formation of interpolymer hydrogen bonds (reversible crosslinking). Because both PVP and PMAA‐co‐EA are amorphous polymers and PEG exhibits crystalline phase, the DSC examination is informative on the phase state of PEG in the triple blends and reveals a strong competition between PEG and PMAA‐co‐EA for interaction with PVP. The hydrogen bonding in the triple PVP–PEG–PMAA‐co‐EA blends has been established with FTIR Spectroscopy. To evaluate the relative strengths of hydrogen bonded complexes in PVP–PEG–PMAA‐co‐EA blends, quantum‐chemical calculations were performed. According to this analysis, the energy of H‐bonding has been found to diminish in the order: PVP–PMAA‐co‐EA–PEG(OH) > PVP–(OH)PEG(OH)–PVP > PVP–H₂O > PVP–PEG(OH) > PMAA‐co‐EA–PEG(? O? ) > PVP–PMAA‐co‐EA > PMAA‐co‐EA–PEG(OH). Thus, most stable complexes are the triple PVP–PMAA‐co‐EA–PEG(OH) complex and the complex wherein comparatively short PEG chains form simultaneously two hydrogen bonds to PVP carbonyl groups through both terminal OH‐groups, acting as H‐bonding crosslinks between longer PVP backbones. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Water‐soluble dual responsive polythiophene‐g‐poly(methoxyethoxy ethyl methacrylate)‐co‐poly(N,N‐diethylamino ethyl methacrylate) for different applications

Polythiophene (PT) based dual responsive water‐soluble graft copolymer (PT‐g‐[poly(methoxyethoxy ethyl methacrylate)‐co‐poly(N,N‐diethylamino ethyl methacrylate)]) (PT‐g‐P(MeO₂MA‐co‐DEAEMA)) (PTDE) has been synthesized by random copolymerization of methoxyethoxy ethyl methacrylate (MeO₂MA) and N,N‐diethylamino ethyl methacrylate (DEAEMA) at 30 °C on the 2,5‐poly(3‐[1‐ethyl‐2‐(2‐ bromoisobutyrate)] thiophene) (PTI) macroinitiator using the Cu based atom transfer radical polymerization technique. The PTDE graft copolymer was characterized by gel permeation chromatography and ¹H NMR techniques and it exhibits thermo‐reversible solubility in water showing a lower critical solution temperature of ca 42 °C in neutral aqueous solution. The PTDE graft copolymer contains a fluorescent PT backbone, and interestingly the system exhibits doubling of fluorescence intensity with rising temperature over the temperature range 41–45 °C at pH 7. The PTDE system therefore acts following the principle of the polymeric AND logic gate and it is also found to be effective in sensing of nitroaromatics, particularly picric acid. The influence of chain hydrophobicity on the logic operation and on the sensing of nitroaromatics is discussed. © 2014 Society of Chemical Industry     

Synthesis and characterization of acrylamide‐based aluminum flocculant for turbidity reduction in wastewater

Polymeric flocculants of aluminum hydroxide‐poly[acrylamide‐co‐(acrylic acid)], AHAMAA, were prepared by solution polymerization using aluminum hydroxide as a coagulant in the presence of acrylamide (AM) and acrylic acid (AA) as a comonomer pair with N,N′‐methylenebisacrylamide as a crosslinking agent. The crosslinking was initiated by ammonium persulfate with N,N,N′,N′‐tetramethylethylenediamine as an initiator. The water absorbency of crosslinked poly[AM‐co‐AA] was always higher than that of AHAMAA and was found to be correlated to the storage modulus of the polymers, which was higher for AHAMAA than that of crosslinked poly[AM‐co‐AA]. The residual aluminum concentration of AHAMAA (0.09–0.2 mg L^?1) indicated the stability of the polymer flocculant which was in good agreement with the observed tan δ and the higher G′′ and G′ values. Both the crosslinked poly[AM‐co‐AA] and AHAMAA satisfactorily reduced the turbidity of kaolin suspensions, but the latter gave a better reduction performance. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Morphology and properties of poly(benzoxazine‐co‐urethane)s based on bisphenol‐S/aniline benzoxazine

Poly(benzoxazine‐co‐urethane) was prepared by melt‐blending bisphenol‐S/aniline‐type benzoxazine (BS‐a) with isocyanate‐terminated polyurethane (PU) prepolymer based on 2,4‐toluene diisocyanate and poly(ethylene glycol), followed by thermally activated polymerization of the blend. The copolymerization reaction between BS‐a and PU prepolymer was monitored using Fourier transform infrared spectroscopy. The morphology, dynamic mechanical properties, and thermal stability of the poly(benzoxazine‐co‐urethane) were studied using scanning electron microscopy, dynamic mechanical analysis, and thermogravimetry. Homogeneous morphology is shown in scanning electron micrographs of the fracture surfaces of poly(benzoxazine‐co‐urethane)s with different urethane weight fractions, and the roughness of the surface increases with urethane content increasing. Correspondingly, a single glass transition temperature (T_g) is shown on the dynamic mechanical analysis curves of the poly(benzoxazine‐co‐urethane)s, and the T_g is higher than that of the polybenzoxazine. With increase in the urethane content, the T_g and water absorption of poly(benzoxazine‐co‐urethane) increase, whereas the storage modulus and thermal stability decrease. POLYM. ENG. SCI., 53:2633–2639, 2013. © 2013 Society of Plastics Engineers     

Effect of primary polymer chain rigidity on intramolecular cyclization and intramolecular crosslinking in free‐radical crosslinking monomethacrylate/dimethacrylate copolymerizations

d‐Bornyl methacrylate (BoMA) was chosen as a typical example of bulky monomethacrylate monomers, the polymerization of which led to the formation of a rigid polymer chain. To discuss the effect of primary polymer chain rigidity on intramolecular cyclization, we compared the solution copolymerization results of BoMA with 1 mol % ethylene dimethacrylate (EDMA; n = 1) and poly(ethylene glycol dimethacrylate) [CH₂?C(CH₃)CO(OCH₂CH₂)_nOCOC(CH₃)?CH₂, n = 9 (PEGDMA‐9)] with those of methyl methacrylate (MMA) with 1 mol % EDMA and PEGDMA‐9; the dependence of the weight‐average degree of polymerization on conversion for the former BoMA copolymerization systems was completely opposed to that for the latter MMA systems, and this was a reflection of a reduced occurrence of intramolecular cyclization caused by the rigidity of the primary polymer chain. The effect of primary polymer chain rigidity on intramolecular crosslinking was discussed through a comparison of both BoMA/EDMA and MMA/EDMA copolymerizations. The correlations of the intrinsic viscosity, root‐mean‐square (rms) radius of gyration, and second virial coefficient with the molecular weight were examined for both BoMA/EDMA (90/10) and MMA/EDMA (90/10) copolymerizations in a dilute solution because microgelation was observed in solution MMA/EDMA (90/10) copolymerization as a reflection of a locally extensive occurrence of intramolecular crosslinking. The logarithmic plots of both the intrinsic viscosity and rms radius of gyration versus the molecular weight for MMA/EDMA copolymerization were compared with those for the corresponding BoMA/EDMA copolymerizations. The second virial coefficients were greater than 10^?5 mol cm³ g^?2 for BoMA/EDMA copolymers, even when the conversion was very close to the gel point, whereas they were quite low, that is, less than 10^?5 mol cm³ g^?2, for an MMA/EDMA copolymer obtained at more than 15% conversion. These were ascribed to a suppressed occurrence of intramolecular crosslinking, a reflection of the lessened flexibility of the polymer main chain and a steric effect due to the bulky d‐bornyl groups. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1086–1093, 2004     

Kinetics of polymerization and particle stabilization mechanism on dispersion copolymerization of styrene and divinylbenzene

Monodisperse highly crosslinked microspheres were prepared by dispersion copolymerization of styrene and divinylbenzene in an ethanol/water medium using poly(N‐vinylpyrrolidone) (PVP) as the stabilizer. The locus of polymerization and growth of particles were investigated. The polymerization kinetics, average particle diameter (D_n), polydispersity index (PDI), and numbers of particles (N_p) were presented. When the initial styrene concentration is below 20%, the results indicate that the polymerization occurs in the particles, and the particles grow to their final size by the diffusion of monomer and oligomer into the existing particles. The polymerization rate can be described by the equation R_p = k[l]^0.87 ([St]^1.91 + [DVB]^0.09) (1 + [PVP]^0.01) exp(? 45.35/RT). The data from infrared spectroscopy demonstrated that the graft stabilizer was present. The dissolution experiments show that the crosslinking reaction occurred irregularly in batch dispersion polymerization. Using the postaddition approach, up to 3% divenylbenzene (DVB) was successfully incorporated in the synthesis of coagulum‐free substance, and monodisperse crosslinked 5 μ m microspheres with a superior resistance to solvents have been prepared. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2230–2238, 2002     

Properties of n‐butyl methacrylate copolymer latex films derived from crosslinked latex particles

Films obtained from copolymer latexes of n‐butyl methacrylate (BMA) with a series of crosslinking monomers [i.e., a macromonomer crosslinker (Mac), ethylene glycol dimethacrylate (EGDMA), and aliphatic urethane acrylate] exhibited differences in their tensile properties and swelling behaviors. For P(BMA‐co‐EGDMA) copolymer, a dependence on the initiator type was obtained. It is postulated that the network microstructures for the various copolymers evolved as the result of the copolymerization reactions between the monomer pairs during the synthesis in the miniemulsion free‐radical copolymerization. These network microstructures are, therefore, hypothesized to influence the mechanical properties of the resultant films. Copolymers prepared with Mac were tough in comparison with copolymers made with EGDMA. The presence of longer linear or lightly crosslinked poly(n‐butyl methacrylate) (PBMA) chains and the looseness of the crosslinked network structures in the PBMA‐co‐Mac copolymers appear to be the factors responsible for the differences. All of the copolymer films disintegrated into swollen individual microgels when they were immersed in tetrahydrofuran. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 42–49, 2003     

Synthesis of poly(chloroprene-co-isobutyl methacrylate) and its compatibilizing effect in polychloroprene/poly(isobutyl methacrylate) blends

A copolymer of chloroprene (CP) and isobutyl methacrylate (iBMA) [poly(CP-co-iBMA)] was prepared in benzene by radical copolymerization. For comparison, the graft copolymer of iBMA onto polychloroprene (CR) [poly(CR-g-iBMA)] was also prepared. The glass transition temperature of the poly(CP-co-iBMA) was about ?32.4°C. The monomer reactivity ratios determined by the Finneman-Ross method were given as r₁ (CP) = 1.80 and r₂ (iBMA) = 0.74 in the copolymerization of CP and iBMA, respectively. Miscibility of blends of CR and poly(isobutyl methacrylate) (PiBMA), prepared by casting from tetrahydrofuran (THF) solution, was investigated by their glass transition temperature behaviors and morphologies. Although the blends of CR and PiBMA were incompatible, the addition of poly(CP-co-iBMA) or poly(CR-g-iBMA) enhanced miscibility between the two base polymers. It was found that the extent of partial miscibility becomes larger when adding poly(CP-co-iBMA) than poly(CR-g-iBMA) as a third component to the CR/PiBMA blend of 50/50 wt % composition. © 1993 John Wiley & Sons, Inc.     

Initiation system effects in the cationic copolymerization of tetrahydrofuran (THF)

Summary Macromonomeric peroxy initiator, poly tetrahydrofuran (poly-THF=inimer) were synthesized via cationic polymerization of THF by the mono- (t-BuBP) and tetra-bromo methyl benzoyl peroxides (BDBP)/ZnCl₂ initiating system. The macromonomers were characterized by ¹H-NMR, IR, and GPC techniques. Methyl methacrylate (MMA) polymerization initiated by poly-THF inimers at 80°C and different times in bulk gave crosslinked poly-THF-b-polymethyl methacrylate block copolymers. Swelling ratios of the crosslinked block copolymers obtained by taking in same amounts of poly-THF inimer and MMA monomer in CHCl₃ were decreased versus time. It was compared the results obtained from t-BuBP-, BDBP-ZnCl₂ initiating systems with t-BuBP-, BDBP-AgSbF₆ initiating systems for THF monomer. Poly(THF-b-MMA) crosslinked block copolymers containing undecomposed peroxide groups initiated the thermal polymerization of styrene, S, were used to obtain poly(THF-b-MM_A-b-S) crosslinked multicomponent copolymers at 90°C. The crosslinked multi component copolymers were investigated sol-gel analysis and swelling ratios in CHCl₃. "Active" poly(THF-b-MM_A) having peroxygen group were used in the free radical coupling reaction of poly butadien (Poly Bd). Poly(THF-b-MM_A)-polybutadien crosslinked blend soluble graft copolymers were obtained. Received: 31 July 2001/Revised version: 16 June 2002/ Accepted: 5 July 2002     

Polyethylene‐block‐poly(ε‐caprolactone) diblock copolymers: synthesis and compatibility

A strategy is introduced for the synthesis of polyethylene‐block‐poly(ε‐caprolactone) block copolymers by a combination of coordination polymerization and ring‐opening polymerization. First, end‐hydroxylated polyethylene (PE‐OH) was prepared with a one‐step process through ethylene/3‐buten‐1‐ol copolymerization catalyzed by a vanadium(III) complex bearing a bidentate [N,O] ligand ([PhN?C(CH₃)CHC(Ph)O]VCl₂(THF)₂). The PE‐OH was then used as macroinitiator for ring‐opening polymerization of ε‐caprolactone, leading to the desired nonpolar/polar diblock copolymers. The block structure was confirmed by spectral analysis using ¹H NMR, gel permeation chromatography and differential scanning calorimetry. The unusual topologies of the model copolymers will establish a fundamental understanding for structure–property correlations, e.g. compatibilization, of polymer blends and surface and interface modification of other polymers. © 2014 Society of Chemical Industry     

Synthesis of comb-shaped copolymers by combination of reversible addition-fragmentation chain transfer polymerization and cationic ring-opening polymerization

Comb-shaped graft copolymers with poly(methyl acrylate) as a handle were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and ring-opening polymerization (ROP) techniques in three steps. First, copolymers of poly(styrene-co-chloromethyl styrene), poly(St-co-CMS), were prepared by RAFT copolymerization of St and CMS using 1-(ethoxycarbonyl)prop-1-yl dithiobenzoate (EPDTB) as RAFT agent. Second, the polymerization of MA using poly(St-co-CMS)-SC(S)Ph as macromolecular chain transfer agent produced block copolymer poly(St-co-CMS)-b-PMA. Third, cationic ring-opening polymerization of THF was performed using poly(St-co-CMS)-b-PMA/AgClO₄ as initiating system to produce comb-shaped copolymers. The structures of the poly(St-co-CMS), poly(St-co-CMS)-b-PMA and final comb-shaped copolymers were characterized by ¹H NMR spectroscopy and gel permeation chromatography (GPC).